Disproportionation of long-chain monoalkyl aromatic compounds

ABSTRACT

THIS DISCLOSURE CONCERNS THE REPARATION OF A HYDROCARBON COMPOSITION CONTAINING A MAJOR AMOUNT OF ALKYL AROMATIC COMPOUNDS HAVING TWO LONG-CHAIN ALKYL GROUPS AND A MINOR AMOUNT OF ALKYL-SUBSTITUTED TETRAHYDRONAPHTHALENES BY THE DISPORTIONATION OF AROMATIC COMPOUNDS HAVING ONE LONG-CHAIN ALKYL GROUP USING ALUMINUM CHLORIDE OR ALUMINUM BROMIDE AS THE CATALYST. THE TERM &#34;LONG-CHAIN REFERS TO LINEAR ALKYL GROUPS CONTAINING FROM ABOUT 8 TO ABOUT 18, PREFERABLY FROM ABOUT 10 TO ABOUT 16, CARBON ATOMS. THE HYDROCARBON COMPOSITION (I.E. DISPROPORTIONATED PRODUCT) IS USEFUL AS A SULFONATION FEEDSTOCK AND AS A LUBRICANT.

May 9, 1972 DISPROPORTIONATION OF LONG-CHAIN MONOALKYL AROMATICCOMPOUNDS MOLES MOLES N 01 a 01 'm l: in Z '0 G. c. FEIGHNER ETAL3,662,012

Filed July 6, 1970 SELECTIVITY CONOENTRATION, MOLE OF MOLE X 2 6O 80 I00I20 I40 I I TIME, MINUTES HT UN DESIRABLES MOLE 60 I 80 I00 I20 I40 I60I80 TIME,MINUTES FIG. 2

. I I1-JVE1- JTOR. GEORGE c. FE/GH/VER GENEE. M06

7 FW W? AGE/VT United States Patent 3,662,012 DISPROPORTIONATION OFLONG-CHAIN MONOALKYL AROMATIC COMPOUNDS George C. Feighner, FranklinLakes, N.J., and Gene E. Nicks, Ponca City, Okla., assignors toContinental Oil Company, Ponca City, Okla.

Continuation-impart of application Ser. No. 529,284, Feb. 23, 1966,which is a continuation-in-part of application Ser. No. 446,661, Apr. 8,1965. This application July 6, 1970, Ser. No. 53,352

Int. Cl. C07c 3/62 U.S. Cl. 260-672 T 24 Claims ABSTRACT OF THEDISCLOSURE This disclosure concerns the preparation of a hydrocarboncomposition containing a major amount of alkyl aromatic compounds havingtwo long-chain alkyl groups and a minor amount of alkyl-substitutedtetrahydronaphthalenes by the disproportionation of aromatic compoundshaving one long-chain alkyl group using aluminum chloride or aluminumbromide as the catalyst. The term long-chain refers to linear alkylgroups containing from about 8 to about 18, preferably from about 10 toabout 16, carbon atoms. The hydrocarbon composition (i.e.disproportionated product) is useful as a sulfonation feedstock and as alubricant.

RELATED APPLICATION This application is a continuation-impart ofapplication Ser. No. 529,284, filed Feb. 23, 19 66, which in turn was acontinuation-in-part of application Ser. No. 446,661, filed Apr. 8,1965, both now abandoned.

In addition to the above application, the following applications, whichhave the same assignee as the present application, are believed to berelated to the subject matter of the present application.

Ser. No. 762,639, filed Sept. 25, 1968, now US. Pat. No. 3,538,177,concerns the disproportionation of monoalkyl aromatic compounds todialkyl aromatic compounds using HFBF as the catalyst. The alkyl groupsof both the monoand dialkyl aromatic compounds contain at least 8 carbonatoms. Use of the HF--BF catalyst produces dialkylbenzenes withoutproducing a significant increase in the amount of alkyl-substitutedtetrahydronaphthalenes over that in the original charge stock.

DISCLOSURE BackgroundField of the invention The present inventionconcerns a process for preparing hydrocarbon compositions containing amajor amount of di-n-alkyl aromatic hydrocarbons, the alkyl groups eachcontaining 8 to 18 carbon atoms. These compositions are especiallyuseful as sulfonation feedstocks for the preparation of oil-solublesulfonates and overbased sulfonates. It is well-known that many usesexist for oilsoluble sulfonatm and overbased sulfonates. For example,oil-soluble sulfonates are useful as rust inhibitors. Millions of poundsof overbased oil-soluble sulfonates are used annually as additives inlubricating oils.

The parent applications (Ser. No. 529,284 and Ser. No. 446,661)disclosed that sulfonates prepared from di-C C -n-alkaryl hydrocarbonshave many improved properties as compared to sulfonates prepared frompostdodecylbenzene. Postdodecylbenzene is a mixture of monoanddi-alkylbenzenes, predominantly mono-alkylbenzenes, the alkyl groups ofwhich are branched-chain.

In addition to being useful as a sulfonation feed-stock hydrocarboncompositions containing a major amount of "ice di-C -C -n-alkarylhydrocarbons are also useful as lowtemperature lubricants (in otherwords Arctic lubricants since they possess the requisite combination oflow pour point, high viscosity index and other properties for this use).Particularly hydrocarbon compositions containing a major proportion ofdi-C -c -n-alkylbenzenes and an eiiective amount (e.g. about 8 to about25 weight percent) of alkyl-substituted tetrahydronaphthalenes ofsimilar molecular weight are very useful as low-temperature lubricants.Such compositions are prepared by the disproportionation, using aluminumchloride as the catalyst, of mono-CrC -n-alkylbenzenes, particularly thepreferred mono C C -nalkylbenzenes as described herein.

Presently, it is believed that the presence of alkyl-substitutedtetrahydronaphthalenes, in a composition comprising di-n-alkylbenzenesand alkyl-substituted tetrahydronaphthalenes has a beneficial eifectwhen the composition is used as a lubricant since the alkyl-substitutedtetrahydronaphthalenes lower the pour point. Moreover, when thishydrocarbon composition is used as a sulfonation feedstock the effect ofthe alkyl-substituted tetrahydronaphthalenes appears to be neutral, i.e.neither beneficial nor detrimental. The alkyl-substitutedtetrahydronaphthalenes appear to sulfonate about as readily as thedi-n-alkylbenzenes.

Since filing the parent application (Ser. No. 529,284) it has beendiscovered that the product prepared by disporportionation of long-chainmonoalkyl aromatic compounds in addition to di-alkyl aromatic compoundscontains a minor, but significant, amount of alkyl-substitutedtetrahydronaphthalenes having molecular Weights similar to the di-alkylaromatic compounds. Moreover, disproportionation produces substantiallymore alkyl-substituted tetrahydronaphthalenes than does alkylation, i.e.the preparation of di-alkyl aromatic compounds by alkylation ofmono-alkyl aromatic compounds.

Also, in the parent application the catalyst was broadly described asbeing a Friedel-Crafts catalyst, with aluminum chloride and aluminumbromide being preferred. Subsequent work has shown that not allFriedel-Crafts catalysts, particularly the Weaker catalysts such asferric chloride, BF alone, BF plus water, aluminum chloridenitrobenzeneand aluminum chloride-nitromethane, result in the disoproportionation ofmono-n-alkylbenzenes to di-n-alkylbenzenes.

The use of HFBF, as a catalyst does result in disproportionation ofmono-n-alkylbenzenes to di-n-alkylbenzenes. However, the use of HFBF asa catalyst requires different operating conditions, particularlytemperature, than does aluminum chloride. More importantly,disproportionation of monoalkylbenzenes using HF-BF does not result in asignificant amount of alkyl-substituted tetrahydronaphthalenes in thedisproportionated product. By contrast, the use of aluminum chloride oraluminum bromide does result in a significant amount ofalkyl-substituted tetrahydronaphthalenes in the disproportionatedproduct.

PRIOR ART According to the references cited in the parent application,Ser. No. 529,284, the following patents are the most pertinentreferences:

US. 2,753,384-Lien et al.-This reference teaches a process for thedisproportionation of mono-n-alkylbenzenes to the correspondingdi-n-alkylbenzenes using HF-BF as the catalyst. According to Lien et al.butyl is the longest alkyl group suitable in their process with propylbeing preferred. In column 4, lines 39-43, Lien et al. state Then-butylbenzenes undergo cracking and other side reactions more readilythan the n-propylbenzenes. In addition Lien et al. state The inventionis limited to the HF--BF treatment of propylbenzene and butylbenzenebecause successful treatment of the pentylbenzene requires differentoperating conditions (col. 5, lines 47- 40).

U.S. 2,993,939Raley et al.-This reference, which is concerned withisomerization of alkylaromatics, teaches that in the prior artisomerization Work AlCl and HF'-BF were considered equivalent asisomerization catalysts.

With regard to this reference applicants believe that it iswell-recognized that isomerization and disproportionation are entirelydiiferent processes.

BRIEF SUMMARY OF THE INVENTION .Broadly stated, the present inventionconcerns a process for preparing alkyl aromatic compounds having twolong-chain alkyl groups by the disproportionation of mono long-chainalkyl aromatic compounds using aluminum chloride or aluminum bromide asthe catalyst.

In one aspect, our invention concerns a process for preparing ahydhocarbon composition containing a major amount of alkyl aromaticcompounds having two longchain alkyl groups and a minor, butsignificant, amount of alkyl substituted tetradhydronaphthalenes ofsimilar molecular weight by the disproportionation of alkyl aromaticcompounds containing one long-chain alkyl group using aluminum chlorideor aluminum bromide as the catalyst.

In another aspect, our invention concerns a process for preparing ahydrocarbon composition containing from about 64 to about 85 weightpercent long-chain dialkylbenzenes and from about 8 to about 25 weightpercent alkyl-substituted tetrahydronaphthalenes of similar molecularweight by the disproportionation, using aluminum chloride or aluminumbromide as the catalyst, of the product resulting from the alkylation ofbenzene with a halogenated, preferably chlorinated, paratfin asdescribed herein.

In still another aspect, our invention concerns the products prepared byany of the processes described in the foregoing.

The term long-chain as used in the foregoing refers to linear alkylgroups containing from about 8 to about 18, preferably from about 10 toabout 16, carbon atoms.

Preferably, the alkyl aromatic compound containing one long-chain alkylgroup and the alkyl aromatic compound containing two long-chain alkylgroups are monon-C C alkylbenzene and di-n-C -C alkylbenzene,respectively.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the rate ofconversion of mono-n-alkylbenzene, and the rate of production ofdi-nalkylbenzenes as the disporportionation reaction proceeds.

FIG. 2 is a graph showing the manner in which the yields ofdi-n-alkylbenzenes and undesirable higher molecular weight productsincrease with increasing disproportionation reaction time and consequentincrease in the extent of conversion of mono-n-alkylbenzene.

The di-n-alkylbenzene fraction described in FIG. 2 also contains a minoramount of alkyl-substituted tetrahydronaphthalenes of similar molecularweight.

DETAILED DESCRIPTION The mono-n-alkaryl compounds In thedisproportionation process of our invention a suitable starting materialconsists essentially of mono-nalkaryl compounds of a certain specificcharacter. More specifically described, these mono-n-alkaryl compoundsare characterized in having an aromatic nucleus which ismono-substituted by a straight-chain or normal alkyl group containingfrom 8 to 18 carbon atoms and attached to the aryl group through asecondary carbon atoms. The aromatic moiety of the incnom alltarylcompounds can be phenyl, tolyl, or Xylyl, but preferably is phenyl. Itis preferable that the alkyl substituents of the compounds contain from10 to 16 carbon atoms and most preferred that the alkyl substituent notdiffer by more than 4 carbon atoms in chain length.

The term mono-n-alkaryl compounds as used herein refers to alkarylcompounds containing one long-chain (C -C alkyl group, it beingunderstood that when the aryl moiety is tolyl one methyl group is on thearomatic nucleus and when the aryl moiety is xylyl two methyl groups areon the aromatic nucleus.

Any mono-n-alkaryl hydrocarbon meeting the description statedimmediately above can be used in our process. Examples of suitable puremono-n-alkaryl hydrocarbons include decylbenzene, undecylbenzene,dodecylbenzene, tridecylbenzene and tetradecylbenzene. In additionmixtures of mono-n-alkaryl hydrocarbons, such as those described, can beused.

A particularly suitable source of starting material is the detergentalkylate described in U.S. Pat. No. 3,316,294. This alkylate is rich inmono-n-alkaryl compounds meeting the definition above, and can be usedin the method of the present invention without further purification ortreatment. Usually the detergent alkylate will contain at least weightpercent mono-n-alkaryl compounds of the type described. Also themouo-n-alkaryl compounds in the detergent alkylate are characterized inhaving at least percent of the alkyl groups bonded to the aryl nucleusthrough a secondary carbon atom of the respective alkyl group.

Briefly, the process of U.S. 3,316,294 comprises the following steps,broadly stated: (a) separating a fraction of substantiallystraight-chain C -C hydrocarbons or fraction thereof from a petroleumdistillate substantially free of olefins and containing saidstraight-chain hydrocarbons together with non-straight chainhydrocarbons, (b) chlorinating said fraction to the extent wherebybetween about 10 and about 35 mole percent of the straightchainhydrocarbons present are substantially only monochlorinated, and (c)alkylating an aromatic compound, e.g. benzene, with the chlorinationproduct of step (b) in the presence of an alkylation catalyst.

Mono-n-alkylbenzenes of the type prepared by U.S. 3,316,294 areavailable under the trademarks Nalkylene 500 and N alkylene 600 fromContinental Oil Company. These particular materials have the followingtypical properties:

NALKYLENE 500 Typical Test value Test method Boiling range F.) 535-595ASTM D-447. grommet nulmber t 1 0. 05 ASTM D-1158.

verage mo ecu ar weig M Color, Saybolt ass Spec Specific gravity (20/20)ASTM D-287. Viscosity (Saybolt seconds) ASTM 88-44.

NALKYLENE 600 Boiliy range F.):

5 580-590 ASIM D-477. 95%; 600-615 ASTM D-477.

Bromine number 1 0.05 PM. #21. Average molecular weight 255-264 Massspec. Color, Saybolt 3 25 PM. #20. Specific gravity 0. 85-0. 87 ASTMD-287. Viscosity (Saybolt seconds) 2 40-46 ASTM 88-44.

1 Maximum.

2 At F.

3 Minimum.

While we believe that we have provided an adequate description of thesalient features of U.S. 3,316,294, in order to make our disclosure evenmore complete this patent is made a part of this disclosure.

THE CATALYST The catalyst in the process of our invention is restrictedto aluminum chloride, aluminum bromide or mixtures thereof. Thediscussion provided under the heading Background-Field of the inventionhas shown why the catalyst is restricted to these materials. Sincealuminum chloride is less expensive it is the preferred catalyst.

A suitable amount of catalyst is from about 0.1 to about 10 weightpercent, based on the monoalkaryl starting material. Preferably, theamount of catalyst is from about 0.5 to about 3 weight percent on thesame basis. When a temperature of 100 C. is employed in the process themost preferred amount of catalyst is about 0.5 weight percent.

When using aluminum chloride or aluminum bromide as a catalyst it isadvantageous to include therewith a small amount of a proton-donormaterial (often called a promoter), such as water or HCl. (This featureis believed to be well-known and, therefore, does not constitute a partof our invention.) In our process the amount of proton-donor material istypically about 4 weight percent based on the weight of catalyst.

PROCESS CONDITIONS While the disproportionation process can be conductedusing a temperature in the range of from about 20 C. to about 130 C., wehave found that more suitably the temperature employed is in the rangeof from about 75 C. to about 120 C. This is because maximum yields ofthe desired disproportionated product are obtained in reasonablereaction times (e.g. 5 to 120 minutes) using these latter-mentionedtemperatures. The most preferred temperature for use in thedisproportionation process is about 100 C. The term disproportionatedproduct refers to the hydrocarbon composition consisting essentially ofdi n-alkyl aromatic hydrocarbons and alkyl-substitutedtetrahydronaphthalenes described elsewhere herein. Also, the termdisproportionated product is equivalent to the term di-n-alkaryl productas described on pages 54 and 55 of Ser. No. 529,284.

The reaction time for the disproportionation process is at least fiveminutes and preferably is in the range of from about thirty minutes toabout three hours, depending upon catalyst level and reactiontemperature.

On the basis of present knowledge it is believed that higher operatingtemperatures result in an increase in the amount of alkyl-substitutedtetrahydronaphthalenes in the disproportionated product.

The disproportionation reaction can be carried out by either acontinuous or a batch process.

When the described preferred conditions and preferred amounts ofmaterial are utilized, from about 30 to 60 mole percent of themono-n-alkaryl starting material is converted to products. The productsinclude di-n-alkaryl compounds, alkyl substitutedtetrahydronaphthalenes, relatively low molecular weight aromaticcompounds, and relatively low molecular Weight branched-chain alkanecompounds. There are also small amounts of undesirable higher molecularweight materials, such as naphthalenes, trialkaryl compounds andpolyphenylalkanes. These higher molecular weight materials are difiicultto separate from the disproportionated product, and lower the yield andquality of the oil soluble sulfonate compositions produced from thedisproportionated product in the manner hereinafter described. We havefound that the quantity of these undesirable high molecular weightproducts can be minimized by controlling the reaction conditions and,particularly, the temperature, amount of catalyst and reaction time, soas to limit the amount of mono-n-alkaryl starting material which isconverted to product to from about 30 to about 50 mole percent. At thisextent of conversion, selectivity to the desired disproportionatedproduct is maximum and is from about 75 percent to 95 percent. This willbe better understood when reference is made to examples hereinafterappearing, and-to the accompanying drawings.

As stated previously herein, the term disproportionated product refersto a hydrocarbon composition consisting essentially ofdi-n-alkylaromatic hydrocarbons and alkyl-substitutedtetrahydronaphthalenes of similar molecular weight.

After cessation of the reaction process the lower boiling benzene andparaifin co-products, and the unreacted monoalkylbenzene, are removed bydistillation. The distillation cut point used to insure removal of theselower boiling components varies, being dependent on the molecular weightof the monoalkylbenzenes. Knowing the molecular weights of themonoalkylbenzenes and the desired disproportionated product anyoneskilled in the art, without undue experimentation, can determine asatisfactory cut point.

Since in the present invention the alkyl groups contain from 8 to 18carbon atoms the distillation cut point for removing unreactedmonoalkylbenzene would vary from that of octylbenzene tooctadecylbenzene. These limits are as follows:

Distillation cut point at 10 mm., 760 mm.,

octylbenzene 270 Octadeeylbenzene 240 425 The above cut points representthe extremes. As one example of a typical usual situation, when startingmaterial is a mixture of C C monoalkylbenzenes (e.g. Nalkylene 600described hereinbefore) the cut point would be about 205 C. at 10 mm. or276 C. at 760 mm.

pressure.

The unreacted mono-n-alkaryl compounds can be recovered from theoverhead and recycled to the process.

THE DISPROPORTIONATED PRO-DUCT wherein R and R contain from 1 to 13carbon atoms each, with the sum of R and R being from about 4 to about14, and R and R contain from 1 to about 16 carbon atoms each, with thesum of R and R 'being from about 7 to about 17. The alkyl groups R R Rand R are predominantly straight chain.

When the starting material is a monoalkylaromatic compound, wherein thearyl moiety is tolyl or xylyl, the alkyl-substitutedtetrahydronaphthalenes in the disproportionated product have a formulasimilar to that shown above except the aryl moiety contains one or twomethyl groups, respectively.

Typically, the disproportionated products, produced by the process ofour invention, have the following chemical composition, as indicated bymass spectrometer analysis:

Component: Percent by weight Dialkaryl compounds 1 64-85Alkyl-substituted tetrahydronaphthalenes 8-25 Indenes, less than 4Diphenylalkanes, less than 5 Naphthalenes and alkyl-substitutednaphthalenes, less than 2 Suitable Preferred 7 v1 ll scosr in ex. Pourpo int, F 5590 -65-80 Molecular weight 350-400 375-385 Similarly, usinga material such as Nalkylene 600 and operating within the processconditions described in the foregoing the disproportioned product (cutpoint of 197 C. at 5 m. Hg) has the following physical properties:

Suitable Preferred viscgsity' 7, 600-17, 600 9, 000-13, 000 24. -37. 028. 0-33. 0 4. 4-6. 1 5. 0-5. 8 105-125 gS-lgg Pour oint, F...- -40-Molec lar weight 375-475 400-460 In order to disclose more clearly thenature of the present invention the following examples, bothillustrative and comparative, are provided. It should be clearlyunderstood, however, that this is done solely by way of example and isnot to be construed as a limitation upon the spirit and the scope of theappended claims.

Examples 1-6 below correspond to Examples 18-23 of Ser. No. 529,284,with the exception that the examples now state that a minor amount ofal-kyl-substituted tetrahydronaphthalenes are present in thedialkylbenzene fraction.

Example 1.200 grams of n-decylbenzene were placed in a 500 ml. flask andheated to a temperature of 75 C. 4 grams of aluminum chloride were thenplaced in the flask with a trace of water and stirring was commenced.After 45 minutes, 53 percent of the n-decylbenzene had reacted to give atotal reaction mixture which, by gas liquid partition chromatography,contained:

Dialkylbenzene 1 35.5

A minor amount of alkyl-substituted tetrahydronaphthalenes was presentin this fraction.

Example 2.--A disproportionation reaction was carried out using theconditions set forth in Example 1 and employing n-decylbenzene as then-alkaryl starting material. Samples were removed from the reactionmixture at minute intervals following the commencement of the re= actionand were analyzed by gas liquid partition chromatography. From thisanalysis, the extent of depletion or conversion of the n-decylbenzenestarting material was determined, and the percent selectivity to thedesired din-decylbenzene product was calculated. The group depicted inFIG. 1 of the drawings illustrates the manner in which the concentrationof the di-n-decylbenzene product 2 and mono-n-decylbenzene startingmaterial varied as the reaction progressed. The graph also shows thevariation with time of the selectivity to the desired di-n-decylbenzene?It will be noted in referring to FIG. 1 that maximum selectivity to thedesired product occurred between about 18 and 58 minutes following thetime of commencement of the reaction. Stated differently, maximumselectivity to the desired di-n-alkaryl product appears to occur at atime when from about 30 mole percent to about 50 mole percent of thestarting material has been converted to product.

It was determined that when the disproportionation reaction is conductedto a stage where less than 30 percent conversion of the startingmaterial has occurred, the amount of catalyst complex sludge which isproduced by the reaction in relation to the total amount of startingmaterial converted to the total amount of starting material converted tothe desired product results in lower selectivity. On the other hand, ifthe reaction is permitted to proceed to the point where over 50 percentconversion of the starting material takes place, the selectivity is alsolowered and a considerably larger concentration of undesirable highmolecular weight compounds results. The relationship of the time overwhich the reaction has proceeded to the concentration in the product ofthe undesirable high molecular weight material is depicted in FIG. 2 ofthe drawings.

Example 3.This example illustrates the preparation of adi-n-alkylbenzene alkylate from a detergent alkylate prepared by theprocess of US. 3,316,294, and corresponding to Nalkylene 600 describedhereinbefore', using the disproportionation procedure. This detergentalkylate was determined by mass spectrometer analysis to have thefollowing composition:

Component: Weight percent Mono-n-alkylbenzene 92.8 DiphenylalkaneTetrahydronaphthalenes 7.1 Naphthalenes 0.1 Average molecular weight 261The detergent alkylate was further analyzed by mass spectrometer and gasliquid partition chromatography for molecular weight distribution andisomeric content as follows:

The detergent alkylate as thus produced was continuously pumped into atwo stage disproportionation reactor unit. One weight percent of AlClcatalyst based on the weight of the detergent alkylate was continuouslyadded to the first reactor stage with a trace of HCl. The reactingmaterial was then permitted to move into the second reactor stage afteraddition of the catalyst. The residence time in the two stage reactorwas 3 hours. Both stages of the reactor were held at 75 C.

A sample of the product developed in the second reactor was collectedand the sludge removed therefrom. Analysis of the sludge-free sampleindicated that disproportionation of the detergent alkylate under theseconditions resulted in a conversion of 33.5 mole percent of thedetergent alkylate starting material. On the basis of the totaldetergent alkylate consumed in the reaction, the weight percent yieldsof the various products with the exception of a very small amount ofhigh molecular weight product were as follows:

1 A minor amount of alkyl-substltuted tetrahydronaphthalenes was presentin this fraction.

Example 4.The di-n-alkylbenzene product of the disproportionationreaction described in Example 3 was isolated by fractionation and wasthen subjected to sulfonation by initially placing 1,500 grams of thedi-n-alkylbenzene and 1,210 grams of 100 pale oil in a reaction flask.This mixture was contacted with 2,250 grams of 20 percent oleum undersulfonation conditions. A yield of 1.2 pound of oil soluble sulfonicacid per pound of the di-nalkylbenzene disproportionation reactionproduct was obtained from the sulfonation reaction.

Example 5.3,000 grams of the detergent alkylate described in Example 3was contacted at 100 C. and for a period of two hours with 15 grams ofaluminum chloride activated by a trace of :HCl. 47 mole percent of thedetergent alkylate was converted to products and the yield ofdi-n-a1kylbenzene was 0.7 pound per pound of the detergent alkylateconsumed.

Example 6.1,000 grams of the detergent alkylate described in Example 3was contacted at 100 C. for a period of 2.5 hours with 5 grams ofaluminum chloride activated by a trace of HCl. 47.3 mole percent of thedetergent alkylate was converted to products and 0.71 pound ofdi-n-alkylbenzene was produced for each pound of the alkylate consumed.

Example 7.This example illustrates the invention and shows that the useof AlCl as the catalyst results in a substantial increase in the amountof tetrahydronaphthalenes.

The monoalkylate composition used as the starting material was producedby the process of US. 3,316,294 and had the following analysis:

Mole or weight percent Monoalkylbenzenes 1 89.5 Tetrahydronaphthalenes10.5

011-014 alkyl groups, with a predominance of Cu. Represented by theformula:

wherein R1 and R2 contain from 1 to 13 carbon atoms each, with the sumof R1 and R2 being from about 4 to about 14.

An amount of 1,500 grams of the monoalkylate composition was charged toan autoclave. To this were added 20 grams AlCl (1.3% by weight based onmonoalkylate) and 0.3 gram water. The contents of the autoclave werestirred for 2 hours while maintaining the temperature at 110 C. Thereaction mixture was then settled and the catalyst withdrawn. Thereaction product was washed with an aqueous base. Following this thereaction product was fractionally distilled using a cut-point of 197 C.at 10 mm. Hg. The product (bottoms fraction) had a yellow to browncolor. It contained 67.1% dialkylbenzenes 3 and 24.4% alkyl-stubstitutedtetrahydronaphthalenes, with the remaining 8.5% being a mixture ofnaphthalenes, dihydronaphthalenes, and diphenylalkanes. The product hadthe following physical properties:

Example 8.This example is comparative and shows that the use of HF-BF asthe catalyst does not result in any substantial increase in the amountof tetrahydronaphthalenes, in the disproportionated product as comparedto the starting material.

The monoalkylate composition used as a starting material (charge stock)was the same as in Example 7.

An amount of 900 grams of the monoalkylate composition was charged to anautoclave. The BF (50 grams) and HF (500 grams) were then added to theautoclave. This reaction mixture was stirred for 1 hour with thetemperature at 25 C. The reaction mixture was then settled and thecatalyst withdrawn. The reaction product was washed with an aqueousbase. Following this the reaction product was fractionally distilledusing a cut-point of 197 C. at 10 mm. Hg. The desired product (bottomsfraction) was water-white. It contained 87.7% dialkylbenzenes and 12.1%alkyl-substituted tetrahydronaphthalenes. It had the following physicalproperties:

Pour point, F. -60 Viscosity at -40 F., cs 6795 Viscosity at F., cs.27.05 Viscosity at 210 F., cs 4.93 Viscosity index 119 Example 9.-Thisexample is comparative and shows the etfect of using catalysts otherthan aluminum chloride or HF--BF complex. In all runs the monoalkylatecomposition was the same as in Example 7. The various catalysts testedand the results obtained are shown below.

Catalyst: Result Ferric chloride N0 disproportionation reaction.

BF (alone) Do.

AlCl -nitrobenzene Do.

HF (alone) Product had very high viscosity at 40 F.

B-F +water No disproportionation reaction.

AlCl -nitromethane Do.

The percent conversion of monoalkylbenzenes to dialkyL benzenes was 45The percent conversion of monoalkylbenzenes to dlalkylbenzenes was 56%Example 10.-This example illustrates the preparation of a large batch ofthe disproportioned product by a continuous reaction process.

The starting material (charge stock) was Nalkylene 600 detergentalkylate described hereinbefore.

The reaction vessel was a 3000-gallon, stirred-kettle reactor, fittedfor heating, controlled addition of liquids and solids and introductionof gaseous materials. Nalkylene" 600 detergent alkylate and A101 werefed continuously to the reaction vessel at rates of 150:s.c.f. perminute. The level of reaction mass in the reactor was maintained toafford a residence time of 1.75 i025 hours. The reaction temperature wasin the range of 90 to 95 C. As the crude product was removedcontinuously from the reactor monitoring by GLPC analysis indicated thatit contained 5 wt. percent benzene, 15 wt. percent paraffins, 55 Wt.percent unreacted monoalkylbenzene and 25 wt. percent dialkylbenzenes.The crude product was allowed to settle and the AlCl sludge was removed.The remaining crude product was then contacted with 2 volumes of 15i10Wt. percent caustic solution. Following this, the crude product wascontacted with 4:1 volumes of water to remove the residual caustic. Theneutralized crude product was then distilled recovering the followingfractions:

benzene70-22S F. at 750 mm. Hg. paraflins225-290 F. at mm. Hg.monoalkylbenzene290-330 F. at 12 mm. Hg. disproportionationproduct-above 330 F. at 12 mm. Hg.

The disporportionation product was subjected to a further fractionationto remove 85:10 wt. percent overhead boiling between 450 and 850 F. at760 mm. Hg. The residue was set aside. The overhead product was thedesired disproportionated product. (164,000 pounds were produced.) Thedisproportionated product had the following physical properties:

By mass spectrometry.

Example 11.A series of comparative runs were made preparingdialkyl'benzene from monoalkylbenzene by disproportionation and byrealkylation. The monoalkylbenzene used in these runs was prepared fromhigh purity individual molecular weight n-paraffin (e.g. a substantiallypure dodecane). The paraffin was first chlorinated, then the chlorinatedparafiin was used to prepared the monoalkylbenzene (by alkylation) Thedialkylbenzenes were prepared by (l) disproportionation of themonoalkylbenzene or (2) alkylation of the monoalkylbenzene with thechlorinated paraffin.

In seven of the ten sets of runs made the product prepared bydisproportionation contained alkyl-substituted tetrahydronaphthalenes.

'Using dodecylbenzene, prepared from n-dodecane as the startingmaterial, the products had the following compositions (volume percent):

Process Dispra- Alkylaportion 0 tion tion Dialkylbenzene. 96 79Alkyl-substituted tetrahydronaphthalenes 2 16 Miscellaneous 2 5 Example12.-This example illustrates the use of aluminum bromide as the catalystin the disproportionation process of our invention.

The starting material (charge stock) was a Nalkylene 600 containing 9.5%tetrahydronaphthalenes, with the remainder being substantially allmono-n-alkyl-benzenes.

The amounts of materials were as follows:

G, Nalkylene 600 265 A1BI'3 1 4.8 HCl (trace) Di-n-alkylbenzene 70.9Alkyl-substituted tetrahydronaphthalenes 23.6 Miscellaneous 5.6

Having thus described the invention by providing specific examplesthereof, it is to be understood that no undue limitations orrestrictions are to be drawn by reason thereof and that many variationsand modifications are Within the scope of the invention.

The invention having thus been described, what is claimed and desired tobe secured by Letters Patent is:

1. A process for preparing alkyl aromatic compounds having two linearalkyl groups, each of which contains from about 8 to about 18 carbonatoms, the aryl moiety of said compounds being selected from the groupconsisting of phenyl, tolyl, xylyl, and mixtures thereof, said processconsisting essentially of:

(a) contacting alkyl aromatic compounds having one linear alkyl groupcontaining from about 8 to about 18 carbon atoms and the aryl moietybeing selected from the group consisting of phenyl, tolyl, xylyl, andmixtures thereof, with from about 0.1 to about 10 weight percent of acatalyst selected from the group consisting of aluminum chloride,aluminum bromide and mixtures thereof, based on said alkyl aromaticcompounds having one linear alkyl group, at a temperature of from about20 C. to about C. and for a time of from about 5 to about minutes,

(b) separating by fractional distillation from the reaction product ofstep (a) said alkyl aromatic compounds having two linear alkyl groups,each of which contains from about 8 to about 18 carbon atoms.

2. The process of claim 1 wherein the reaction temperature of step (a)is from about 75 to about 120 C.

3. The process of claim 2 wherein the catalyst is aluminum chloride andthe amount of catalyst is from about 0.5 to about 3 weight percent.

4. The process of claim 3 wherein the reaction time of step (a) is fromabout 30 to about 180 minutes.

5. The process of claim 4- wherein the linear alkyl group of the alkylaromatic compounds of step (a) and both linear alkyl groups of the alkylaromatic compounds of the product in step (b) contain from about 10 toabout 16 carbon atoms.

6. The process of claim 5 wherein the reaction tempera ture is about 100C.

7. A process preparing dialkylbenzenes having two linear alkyl groupseach of which contains from about 8 to about 18 carbon atoms whereinsaid process consists essentially of:

(a) contacting monoalkylbenzenes, the alkyl groups of which contain fromabout 8 to about 18 carbon atoms and are linear with from about 0.1 toabout 10 Weight percent of a catalyst selected from the group consistingof aluminum chloride, aluminum bromide and mixtures thereof, based onsaid monoalkylbenzenes, at a temperature of from about 20 C. to about130 C. and for a time of from about to 180 minutes,

(b) separating by fractional distillation from the reaction product ofstep (a) said dialkylbenzenes.

8. The process of claim 7 wherein the reaction temperature of step (a)is from about 75 to about 120 C.

9. The process of claim 8 wherein the catalyst is aluminum chloride andthe amount of catalyst is from about 0.5 to about 3 weight percent.

10. The process of claim 9 wherein the alkyl group of themonoalkylbenzenes and both alkyl groups of the dialkylbenzenes containfrom about 10 to about 16 carbon atoms.

11. The process of claim 10 wherein the alkyl groups of themonoalkylbenzenes and both alkyl groups of the dialkylbenzenes areattached to the benzene ring through a secondary carbon atom.

12. The process of claim 11 wherein the reaction temperature is about100 C.

13. -A process for preparing a hydrocarbon composition containing amajor amount of alkyl aromatic compounds, said compounds having twolinear alkyl groups containing from about 8 to about 18 carbon atoms andthe aryl moiety being selected from the group consisting of phenyl,tolyl, xylyl and mixtures thereof, and a minor amount of alkylsubstituted tetrahydronaphthalenes, said process consisting essentiallyof:

(a) contacting alkyl aromatic compounds having one linear alkyl groupcontaining from about 8 to about 18 carbon atoms and the aryl moietybeing selected from the group consisting of phenyl, tolyl, xylyl, andmixtures thereof, with from about 0.1 to about 10 weight percent of acatalyst selected from the group consisting of aluminum chloride,aluminum bromide and mixtures thereof, based on said alkyl aromaticcompounds having one linear alkyl group, at a temperature of about 20 C.to about 130 C. and for a time of from about 5 to about 180 minutes,

(b) separating .by fractional distillation from the reaction product ofstep (a) said hydrocarbon composition containing a major amount of alkylaromatic compounds having two linear alkyl groups and a minor amount ofalkyl substituted tetrahydronaphthalenes.

14. The process of claim 13 wherein the product is a hydrocarboncomposition containing from about 64 to about weight percent alkylaromatic compounds having two linear alkyl groups and from about 8 toabout 25 weight percent alkyl-substituted tetrahydronaphthalenes.

15. The process of claim 14 wherein the reaction temperature of step (a)is from about 75 to about C.

16. The process of claim 15 wherein the catalyst is aluminum chlorideand the amount of catalyst is from about 0.5 to about 3 weight percent.

17. The process of claim 16 wherein the reaction temperature is about100 C.

18. A process for preparing a hydrocarbon composition containing fromabout 64 to about 85 weight percent dialkylbenzenes the alkyl group ofwhich contain from about 8 to about 18 carbon atoms, and from about 8 toabout 25 weight percent alkyl-substituted tetrahydronaphthalenes, saidprocess consisting essentially of:

(a) contacting monoalkylbenzenes, the alkyl groups of which contain fromabout 8 to about 18 carbon atoms and are linear, with from about 0.1 toabout 10 weight percent aluminum chloride or aluminum bromide catalyst,based on said monoalkylbenzenes, at a temperature of from about 20 C. toabout C. and for a time of from about 5 to about minutes,

(b) separating by fractional distillation from the reaction product ofstep (a) said hydrocarbon composition containing from about 64 to about85 weight percent dialkylbenzenes and from about 8 to about 25 weightpercent alkyl-substituted tetrahydronaphthalenes.

19. The process of claim 18 wherein the reaction temperature of step (a)is from about 75 to about 120 C.

20. The process of claim 19 wherein the catalyst is aluminum chlorideand the amount of catalyst is from about 0.5 to about 3 weight percent.

21. The process of claim 20 wherein the reaction temperature is about100 C.

22. The product prepared by the process of claim 1.

23. The product prepared by the process of claim 13.

24. The product prepared by the process of claim 20.

References Cited UNITED STATES PATENTS 3,518,321 6/1970 Peterson 260-672T 3,538,177 11/1970 Nicks 260 -672 T 3,538,178 11/1970 Sias 260-672 TCURTIS R. DAVIS, Primary Examiner US. Cl. X.R. 260-505 A, 671 G

